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Why the heck is the Mamquam River so milky?

Hint: It is all about the glacial melt.

All summer long, locals have noted that the Mamquam River looked more grey and milky, or turbid than usual.

We are used to seeing it get this way occasionally, but this was a sustained thing, week after week, and month after month.

Murray Manson, the section head of the Fisheries Department's Habitat Restoration Centre of Expertise, told The СÀ¶ÊÓƵ he had been on a helicopter tour last week to investigate the issue.

To understand the situation, you have to visualize the geography of the area.

Beside the dormant volcano, Mount Garibaldi (Nch'ḵay̓ in the Squamish language), is a cinder cone called the Opal Cone, located on the southeast flank of Mount Garibaldi.

"The Opal Cone is kind of wrapped on the north side by a huge glacier, that's the Garibaldi Névé," Manson said.

"That glacier is receding. And so we saw just some dramatic areas where the glacier has receded, and all the water that's running off from that melting ice is cutting through what looks like ash deposits because it's such a volcanic area."

Manson noted that the way the glacier runoff travels, it all goes down Zigzag Creek, which goes to Skookum Creek, which flows to the Mamquam River.

"You can follow that all the way up. It is all coming from Zigzag Creek."

Manson said that what struck him about this situation was that 15 years ago, it was Ring Creek that was flowing milky.

"And now the glacier has receded so far that it's no longer flowing down Ring Creek ... because it's receded back over a divide; so there's no more runoff through the ash that was over on top of Ring Creek," he said.

"It is staggering to go out there. It is a beautiful area, a beautiful glacier that is just disappearing."

He said that with a warm summer in 2023 and then the low snowpack, the glacier has been melting away.

"I think that last year there was a huge amount of ice that melted off over the summer, and then it got snowed on, froze up for the winter, but then once that snow melted out this year, all that area that was exposed last year, the water is just running through it and carrying the ash and fine sediments away, and that's why you're seeing it that colour."

See more on this topic in our sister publication Pique Newsmagazine's story 

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